Just a suggestion, Look at joining the Elks, they have a lodge with elect and water sites in the back for visiting members at 20 a night. We stayed last year and it was only 20 minutes from the national mall. We drove in to DC and parked in the IRS underground parking for either 10 or 20 a day. So, for 40 dollars a day, we had a nice overnight spot and a close in safe secure parking stop.
Your membership is good for a year, and a number of the lodges have sites set-up for over night stops/stays.
DC is just plain expensive. In the big picture of things $65 per night for Cherry Hill is actually cheap!!
We have done it both ways, camp and stay in a downtown hotel, and on a hotel on metro line in Virgina.
In the end I think staying in a hotel is more efficient, easier and maybe even more cost effective. You are where the action is.
You get up in the am and walk to where you want to go, take the Metro or even a cab. You can stay out late, visit the Lincoln Memorial at night etc. You can cover so much more ground in a shorter time, two days instead of three.
When time does not matter we stay at Greenbelt, but we are self contained including solar and very low electrical demand.
Sometime staying in the RV just is not the best, this is one of those rare occasions.
I can second both Pohick Bay & Bull Run! Great parks and fairly easy to access the metro. I live kind of in between both parks and have been to both.
My recommendation is don't drive in DC! The metro is fairly affordable and if you get there early (or late say, afternoon) you should be able to find parking at either Vienna or Franconia-Springfield. The Franconia-Springfield station just built a new parking structure and you can park at the Macy's at the Springfield Mall and walk if you need to. They also have parking at the Huntington Station in Alexandria, which isn't too far from the Franconia-Springfield station.
I'd also recommend Prince William Forest Park - it's a little further out down 95 but it's a National Park and it has a small, primitive - no hook ups - campground in the park and there's the Prince William Travel Trailer Village for bigger RVs. The place for big RVs is out of the park on a main road - easy access to 95 and it's run by a park concessionaire.
I just returned home from 3 nights and Cherry Hill and I was a little disappointed. The park is well kept and the people are fantastic BUT wow is it loud. All you hear is truck traffic 24/7. I had to wear ear plugs at night to sleep. With that said I still think its the best option in the DC area.
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I know Cherry Hill is the favorite by a ways but I'll give another vote for Bull Run Regional Park, Manasses. 20 min from the metro Vienna station, free parking?, 20 minutes from the Air & Space Museum, Dulles, where all the big stuff is.
Nice quiet CG, well...quiet when the gun range closes for the evening. No traffic noise.
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I like Bull Run Regional Park. It's right off of I-66 which makes it easy to get to a metro center or to drive into the city.
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